So first off - regarding American Airlines... MOST of the strategies that people were using to earn large amounts of miles don't work anymore. So it would be difficult to do something to get shutdown now. If I were starting out fresh with them I wouldn't have a lot of worry about earning 2-3 bonuses on different cards across the Barclays and Citi portfolio.
I'm not going to try to navigate the waters of international travel here because that is way out of my area of expertise. What I will say is that there are a BUNCH of Delta cards, and that Amex MRs transfer to Delta. If I recall, you hold at least one BBP (or do you both have one)? You could cross-support to Delta cards from that BBP and get some MRs out of it too (I think 10k MRs). Amex Business cards are even better because they won't affect your Chase pacing or 5/24 status. You of course still need to keep in mind the general Amex guidelines to avoid being labeled a "gamer" (including keeping up that spend AFTER the MSR to avoid future pop-up restrictions).
URs obviously are easy to earn right now too with a plethora of UR earning cards out there BUT you can only run so fast (as you're quickly figuring out).
The good news is you're looking at 2022 so you have a lot of time to figure this out! You're starting now which is good...a lot of people show up on the scene looking for a way to earn miles for a 2020 int'l trip and to paraphrase the great
@calypso726, that probably isn't going to work out too well for you!